Assessing tiger population made easy

 The technology, developed by tiger expert Dr Ullas Karanth, N Samba Kumar  and Arjun M Gopalaswamy from WCS and Dr Uma Ramakrishnan, Samrat Mondal and others of NCBS will help assess populations by identifying individual animals using the DNA signatures found in the excreta of the animals.

Earlier DNA was collected from blood or tissue samples from tigers that were darted or sedated. According to the researchers, this new non-invasive technique represents a powerful new tool for measuring the success of future conservation efforts.

"This study is a breakthrough in the science of counting tiger numbers, which is a yardstick for measuring conservation success," said Ullas Karanth. "The technique will allow researchers to establish baseline numbers on tiger populations in places where they have never been able to accurately count them before." he added.

Dr Ravi Chellam, Country Director, WCS, India Programmes said, "Earlier scats were used to determine the prey of the animals, but now scat collected using specific techniques enables to arrive at the near accurate figure of the animal as the fecal matter of the animal contains certain amount of DNA, which can help assess the population." 

Speaking on the advantage of the technology, Dr Chellam said that the DNA sampling has established 26 tigers at Bandipur, while the existing latest technology, the camera-trap, had put the figures to 29 earlier. This is indeed a satisfying and comparable statistics, because arriving at an accurate figure is near impossible due to several reasons, he said.

The study took place in India's Bandipur Reserve in Karnataka, a long-term WCS-CWS research site that supports a high abundance of tigers.

Accordingly, researchers collected 58 tiger scats following rigorous protocols, then identified individual animals through their DNA. Tiger populations were then estimated using sophisticated computer models. These results were validated against camera trap data, where individual tigers are photographed automatically and identified by their unique stripe pattern. Camera-trapping is considered the gold standard in tiger population estimation, but is impractical in several areas where tiger densities are low or field conditions too rugged. "We see genetic sampling as a valuable additional tool for estimating tiger abundance in places like the Russian Far East, Sunderban mangrove swamps and dense rain forests of Southeast Asia where camera trapping might be impractical due to various environmental and logistical constraints," said Dr Karanth.